// 拖拽的指令
const drag = {
  beforeMount(el: any, binding: any) {
    // 自定义属性，判断是否可拖拽
    if (!binding.value) {
      return
    }
    const dialogHeaderEl = el.querySelector('.dialog_header')
    const dragDom = el.querySelector('.dialog_content')

    dialogHeaderEl.style.cssText += ';cursor:move;'
    // dragDom.style.cssText += ';bottom:0px;'

    // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
    const sty = (function () {
      if (document.body) {
        // 在ie下兼容写法
        return (dom: any, attr: any) => dom.currentStyle[attr]
      }
      return (dom: any, attr: any) => getComputedStyle(dom, null)[attr]
    })()

    dialogHeaderEl.onmousedown = (e: any) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft
      const disY = e.clientY - dialogHeaderEl.offsetTop
      const screenWidth = document.body.clientWidth // body当前宽度
      const screenHeight = document.documentElement.clientHeight // 可见区域高度(应为body高度，可某些环境下无法获取)

      const dragDomWidth = dragDom.offsetWidth // 对话框宽度
      const dragDomheight = dragDom.offsetHeight // 对话框高度

      const minDragDomLeft = dragDom.offsetLeft
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth

      const minDragDomTop = dragDom.offsetTop
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight

      // 获取到的值带px 正则匹配替换
      let styL = sty(dragDom, 'left')
      // 为兼容ie

      if (styL === 'auto') {
        styL = '0px'
      }
      let styT = sty(dragDom, 'top')

      // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
      if (styL.includes('%')) {
        styL = Number(document.body.clientWidth) * (Number(styL.replace(/%/g, '')) / 100)
        styT = Number(document.body.clientHeight) * (Number(styT.replace(/%/g, '')) / 100)
      } else {
        styL = Number(styL.replace(/px/g, ''))
        styT = Number(styT.replace(/px/g, ''))
      }

      document.onmousemove = function (e) {
        // 通过事件委托，计算移动的距离
        let left = e.clientX - disX
        let top = e.clientY - disY
        // 边界处理

        if (-left > minDragDomLeft) {
          left = -minDragDomLeft
        } else if (left > maxDragDomLeft) {
          left = maxDragDomLeft
        }

        if (-top > minDragDomTop) {
          top = -minDragDomTop
        } else if (top > maxDragDomTop) {
          top = maxDragDomTop
        }

        // 移动当前元素
        dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`
      }

      document.onmouseup = function (e: any) {
        document.onmousemove = null
        document.onmouseup = null
      }
      return false
    }
  }
}
// 挂载，注册
const directives = {
  install: function (app: any) {
    app.directive('dialogDrag', drag)
  }
};

export default directives;
